I understand that it is possible to put a 235 head on a 261 block to raise the compression ratio (7.8:1 on the 261), as long as one drills out steam holes in the 235 head to match those in the 261 block.
1. Has anyone successfully done this?
2. Does anyone know the combustion chamber cc's of a stock 235 head? 3. Did the cc volume in the 235 head vary at all according to the year?
4. How much raise in compression can one expect to achieve if:
I were to bolt a 235 head on, unmilled, on a stock bore 261?
To my knowledge, the 261 has the same 3 15/16 stroke as the 235, it is just bored out (and beefier in the low end).
I am trying to use one of the online calculators, trying to work backwords to try and see what the 235 cc volume might be given the 235's 3.5634 inch bore (3 9/16) and 3.9375 (3 15/16) inch stroke.
I am coming up with the 261 combustion chamber having to be about 95-97 cc's That can't be right, could it be that big?
I am also coming up with about 84cc's for the 261 head to achive the 8:1 compression ratio.
If that is correct, then putting an unmilled 235 head on a 261 should yield about an 8.75:1 ratio. Mill it and you have close to 9:1, which is just what I want. Bore it .030 over and you have a little more.
Am I way off here? Could someone please correct me if I am in error? Thanks a lot
